CVE-2002-1842 in Perlbot
Summary
by MITRE
Perlbot 1.0 beta allows remote attackers to execute arbitrary commands via shell metacharacters in (1) a word that is being spell checked or (2) an e-mail address.
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Analysis
by VulDB Data Team • 07/04/2024
The vulnerability identified as CVE-2002-1842 affects Perlbot 1.0 beta, a web-based spell checking application that processes user input through shell commands for spell checking operations. This represents a classic command injection flaw that allows remote attackers to execute arbitrary system commands on the affected server. The vulnerability manifests when the application processes user-supplied input without proper sanitization or validation, specifically during spell checking operations and email address validation. The attack vector exploits the application's reliance on shell commands for spell checking functionality, creating an opportunity for malicious input to be interpreted and executed as system commands rather than being treated as plain text.
The technical implementation of this vulnerability stems from improper input handling within the Perlbot spell checking module. When users submit words for spell checking or provide email addresses, the application directly incorporates these inputs into shell command executions without adequate sanitization. This design flaw aligns with CWE-77, which describes improper neutralization of special elements used in OS commands, and CWE-94, which covers improper control of generation of code. The vulnerability exists because the application fails to properly escape or filter shell metacharacters such as semicolons, ampersands, backticks, and other special characters that could alter the intended execution flow of shell commands. Attackers can leverage this weakness by embedding malicious shell commands within spell check requests or email addresses, effectively bypassing normal application security controls and gaining unauthorized access to the underlying system.
The operational impact of this vulnerability is severe as it provides remote attackers with arbitrary code execution capabilities on the affected system. An attacker could potentially gain full control over the server hosting Perlbot, allowing for data theft, system compromise, privilege escalation, and persistence mechanisms. The vulnerability affects both spell checking functionality and email validation processes, expanding the attack surface and increasing the likelihood of successful exploitation. From an adversarial perspective, this vulnerability maps to several ATT&CK techniques including T1059.001 for command and script interpreter execution, T1068 for local privilege escalation, and T1566 for social engineering through spearphishing. The remote nature of the attack means that exploitation can occur from any location without requiring physical access to the system, making it particularly dangerous for web applications.
Mitigation strategies for this vulnerability require immediate implementation of proper input validation and sanitization mechanisms. The primary defense involves escaping or filtering shell metacharacters from all user inputs before they are processed by shell commands. This approach aligns with the principle of least privilege and input validation best practices recommended by security frameworks. Organizations should implement proper shell escaping functions such as using system call variants that do not invoke shell interpretation, or employing parameterized command execution methods. Additionally, the application should be updated to remove or disable the vulnerable spell checking functionality until proper sanitization measures are implemented. Network segmentation and firewall rules can provide additional defense in depth, while monitoring systems should be configured to detect unusual command execution patterns. The vulnerability also highlights the importance of secure coding practices and regular security assessments, particularly for applications that invoke shell commands with user-supplied data, as outlined in OWASP Top 10 and NIST cybersecurity guidelines.